As candidates for a next-generation lithography technique in a semiconductor element manufacturing process, a double patterning technique by means of ArF-immersion exposure, EUV lithography, nanoimprinting, and the like are known. These lithography techniques have held a variety of problems such as a cost increase and through-put deterioration in association with increased fineness of a pattern.
Under these circumstances, self-assembly (DSA: Directed Self-Assembly) has been expected to be applied to the lithography technique. Since the self-assembly occurs due to a voluntary behavior of energy stabilization, a pattern with high dimensional accuracy can be formed. In particular, a technique of applying microphase separation of a high-polymer block copolymer enables formation of periodic structures in a variety of shapes of several to several hundred nm (nanometers) by simple coating and anneal processes. By transforming the high-polymer block copolymer into a spherical shape, a cylindrical shape, a lamellar shape or the like in accordance with a composition ratio of its block, and changing the size of the copolymer in accordance with its molecular weight, it is possible to form a dot pattern, a hole or a pillar pattern, a line pattern, or the like, having a variety of dimensions.
In order to form a desired pattern in a broad range by means of DSA, it is of necessity to provide a guide for controlling a generation position of a polymer phase formed by self-assembly. As the guide known are: a physical guide (graphoepitaxy) which has a concavo-convex structure with respect to the substrate surface and forms a microphase-separation pattern in its concave portion; and a chemical guide (chemical epitaxy) which is formed to be an underlayer of the DSA material and controls, based on a difference in its surface energy, a formation position of the microphase separation pattern.
Since the microphase separation pattern is formed with respect to a previously formed guide pattern, its alignment to a foundation pattern (underlying pattern) as an ultimate aligned object is indirect alignment, thereby causing low alignment accuracy.